The present invention relates generally to solid oxidizer tablets such as those used in toilet tanks, and more particularly to an oxidizer tablet that provides a signal when it is time to add fresh oxidizer to the tank.
It is well known to the art to use chemical oxidizers, and particularly halogen-releasing compositions, to clean toilet bowls and tanks. These oxidizers may be used in long-life, solid form by placing a tablet or puck in the tank (or in a dispenser in a tank) where it slowly dissolves to treat the water.
The useful life of these solid compositions is generally determined by the rate at which the oxidizer dissolves into the water. As a general rule then, when solid oxidizer material remains in the tank the oxidizer is still acting to oxidize contaminants, clean surfaces, and in some cases sanitize the water. Accordingly, the user can theoretically determine whether the oxidizer is working in the water by observing whether solid oxidizer remains in the tank.
Since toilet tanks are commonly designed so that the contents are hidden from view, it is generally inconvenient to observe whether solid oxidizer remains in the tank. Thus, products using coloring agents to signal the useful life of the oxidizer have been developed for use in toilet tanks. However, since most coloring agents and pigments are not stable when packaged with oxidizers, it has heretofore been necessary to package the coloring agent and the oxidizer separately.
For example, commercially available products that use two separately packaged tablets (one oxidizing tablet and one color-releasing tablet) include VANiSH(copyright) Blue and Bleach (S.C. Johnson and Son, Inc.), CLOROX(copyright) Blue and Bleach (The Clorox Company), and 2000 Flushes(copyright) (Global Household Brands). All three of these products use C.I. Acid Blue 9, which is unstable when mixed or stored in contact with oxidizers.
A need therefore exists for a single oxidizer puck or tablet that provides a visual indicator of oxidizer activity (as defined by the presence of solid oxidizer) when used in a tank hidden from view. The present invention addresses that need.
Briefly describing one aspect of the present invention, there are provided solid oxidizer compositions that provide a signal when it is time to add more oxidizer. The preferred compositions comprise an oxidizer shell with a coloring agent disposed therein. The coloring agent is substantially color stable when stored in the oxidizer shell, and the oxidizer shell is formed and shaped to enclose the coloring agent in a manner in which the coloring agent is prevented from dispersing into the water in the tank until the oxidizer shell is substantially dissolved.
One object of the present invention is to provide an oxidizer tablet that provides a signal when the oxidizer is substantially dissolved and needs to be replaced.